return values.get(0);
    }

    public void exit() {
        if (values.isEmpty()) {
            throw new IllegalStateException();
        }
        values.remove(0);
    }

    public <T> void seed(Class<T> clazz, Provider<T> value) {
        getScopeState().seed(clazz, value);
    }

    public <T> void seed(Class<T> clazz, final T value) {
        seed(clazz, (Provider<T>) () -> value);
    }

import org.apache.maven.api.services.ModelBuilderRequest;
import org.apache.maven.api.services.ModelProblemCollector;

/**
 * Handles inheritance of model values.
 *
 */
public interface InheritanceAssembler {

    /**
     * Merges values from the specified parent model into the given child model. Implementations are expected to keep

                }
            });
        }
    }

    @Override
    public Iterator<Lifecycle> iterator() {
        return values.values().iterator();
    }

    @Override
    public Stream<Lifecycle> stream() {
        return values.values().stream();
    }

    static <T> List<T> concat(List<T> l, T t) {
        List<T> nl = new ArrayList<>(l.size() + 1);
        nl.addAll(l);

            Map<Plugin, Plugin> allPlugins = new LinkedHashMap<>();
            plugins.values().stream().flatMap(pc -> pc.getPlugins().stream()).forEach(p -> addPlugin(allPlugins, p));
            Model lifecycleModel = Model.newBuilder()
                    .build(Build.newBuilder().plugins(allPlugins.values()).build())
                    .build();
            return merger.merge(model, lifecycleModel);
        }
    }

                    T extends ExtensibleEnum, P extends ExtensibleEnumProvider<T>>
            implements ExtensibleEnumRegistry<T> {

        protected final Map<String, T> values;

        DefaultExtensibleEnumRegistry(List<P> providers, T... builtinValues) {
            values = Stream.<T>concat(
                            Stream.of(builtinValues), providers.stream().flatMap(p -> p.provides().stream()))

 * Handles injection of dependency management into the model.
 *
 */
public interface DependencyManagementInjector {

    /**
     * Merges default values from the dependency management section of the given model into itself.
     *
     * @param model The model into which to merge the values specified by its dependency management sections, must not
     *            be <code>null</code>.

the description. Description appendValue(java.lang.Object value) Appends an arbitary value to the description. <T> Description appendValueList(java.lang.String start, java.lang.String separator, java.lang.String end, java.lang.Iterable<T> values) Appends a list of values to the description. <T> Description appendValueList(java.lang.String start, java.lang.String separator, java.lang.String end, T... values) Appends a list of values to the description. Methods inherited from class java.lang.Object...

import org.apache.maven.api.services.ModelBuilderRequest;
import org.apache.maven.api.services.ModelProblemCollector;

/**
 * Replaces expressions of the form <code>${token}</code> with their effective values. Effective values are basically
 * calculated from the elements of the model itself and the execution properties from the building request.
 *
 */
public interface ModelInterpolator {

    /**

            <!-- NOTE: These values are deliberately not in alpha order! -->
            <stringParam>CHILD-1</stringParam>
            <stringParam>CHILD-3</stringParam>
            <stringParam>CHILD-2</stringParam>
            <stringParam>CHILD-4</stringParam>
          </stringParams>
          <listParam combine.children="append">
            <!-- NOTE: These values are deliberately not in alpha order! -->

            <!-- NOTE: These values are deliberately not in alpha order! -->
            <stringParam>CHILD-1</stringParam>
            <stringParam>CHILD-3</stringParam>
            <stringParam>CHILD-2</stringParam>
            <stringParam>CHILD-4</stringParam>
          </stringParams>
          <listParam combine.children="append">
            <!-- NOTE: These values are deliberately not in alpha order! -->